London bicycle storage

I will be visiting London twice in a six-twelve month period. Rather than ship my bike from/to the USA for each trip, I had rather place it in storage in London between trips. Does anyone have any suggestions where I can store my bike? Thanks.

Another option might be to join the warm showers list (a hospitality list for touring cyclists), then try to contact members around London. Offer a fee for the storage, as this may inconvenience the host, as compared to just an overnite stay of a guest. Google: Warm showers list.